Setting downhole tools has in the past involved mechanical movements that are actuated by rotation, pulling, setting down weight or by tools that hang onto one component while driving another mounted to it. Other motive forces have been hydrostatic pressure, explosive charges and various forms of stored potential energy that is released at the appropriate time to set a tool.
More recently downhole tools such as packers have been set with expansion of the underlying mandrel from within. The sealing element is simply pushed out to contact the tubular in the surrounding wellbore or against the formation if it set in an open hole portion of the wellbore. While expansion applies a radial force to push the sealing element into a sealing contact, mere radial expansion simply brings a sealing element into proximity of the surrounding tubular or the wellbore but does not necessarily apply or more specifically maintain a longitudinal compressive force on the sealing element to help it maintain the seal.
The present invention seeks to take advantage of the longitudinal shrinkage that results from radial expansion. A body is mounted to the radially expanding mandrel that accommodates such expansion while retaining its longitudinal length or at minimum, not shrinking the same amount. The relative movement thus created, in the case of a packer, adds an element of compressive force longitudinally apart from the expansion force that acts radially. The underlying mandrel is then subjected to a residual longitudinal tensile force. As a result the packer can better continue to maintain a seal in cased or open hole. Other tool applications are envisioned beyond packers to take advantage of the relative movement made available between an expanding element and an adjacent sleeve that grows with it radially but does not shrink longitudinally to the same or any degree. Those skilled in the art will appreciate the full scope of the invention better from a review of the description and drawings of the preferred embodiment which appear below, with the understanding that the appended claims define the invention.